Answered June 9th, 2019

Howie Kendrick, Trea Turner, Adam Eaton and Anthony Rendon went back-to-back-to-back-to-back in the 8th inning, making the Washington Nationals the first franchise to hit four consecutive homers twice after first accomplishing it in 2017.

What are the Nationals' most HR in a game in the 8th inning or later?
Interpreted as:
What are the Nationals' most HR in a regular-season game in the 8th inning or later?